Expression of tenascin in the developing human small intestine.

The expression of tenascin (Tn), an extracellular matrix glycoprotein, was analyzed in the human small intestine. Three major oligomeric forms of intestinal Tn (320 kDa, 220 kDa and 200 kDa) were identified in both the fetus and the adult. The intestinal 200 kDa form was not found expressed by intestinal mesenchymal cells in culture. During development, the amounts of the 320 and 220 kDa forms remained relatively constant between 9-20 weeks of gestation as compared to sucrase-isomaltase and a-smooth muscle actin while the 200 kDa immunoreactive component increased substantially during this period of active intestinal morphogenesis. Further experiments by microdissection revealed that the 200 kDa component was the major form of Tn in the intestinal villus. These results suggest that this newly identified 200 kDa form of Tn in the small intestine is predominantly expressed in the villus under a developmentally regulated pattern.